1. Field of the Invention
This invention relates to the field of explosives and, in particular, is directed to compositions designed as substitutes for or additives in the current field explosive standard, composition C-4. This invention is also directed to a process for using the explosive compositions of this invention.
2. State of the Art
Nitramines are highly energetic compounds that have found wide acceptance in the art of explosives. Perhaps the most common nitramines in use in the explosives art today are 1,3,5-trinitro-1,3,5-triaza-cyclohexane (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetraaza-cyclooctane (HMX). RDX is well known for its use in composition CA, which is a combination of RDX, polyisobutylene, a plasticizer such as either dioctyladipate (DOA) or di(2-ethylhexyl)sebacate, and fuel oil. Composition C-4 has low impact sensitivity, is capable of being cut to desired sizes with relative ease, and can be directly adhered to a wide array of explosive sites. These properties make composition C-4 especially suitable for field operations.
There are, however, certain drawbacks to the use of composition C-4. Drawbacks of composition C-4 include its relatively low deformability at room temperature and its poor low temperature properties. For example, in field operations, composition C-4 cannot be readily forced into small holes. In a manufacturing environment, composition C-4 lacks the physical properties to permit its room-temperature injection through narrow passageways, such as an injection passageway or runner for a shaped-charge warhead. As a consequence, composition C-4 must be either heated to a sufficiently high temperature to increase its extrudability or cut to sufficiently small dimensions to permit its insertion into and through small spaces. Due to the hazardous and sometimes unforeseeable happenings that occur in field operation, it is often infeasible or impractical to heat composition C-4 to a sufficient temperature and for a sufficient period of time to lower its viscosity. Further, loading composition C-4 as a shaped charge into a warhead requires high compaction pressures in order to minimize the presence of voids between the warhead case and the composition C-4 charge. Even with precision loading, small voids still commonly remain.
U.S. Pat. No. 4,293,351 discloses a pliable and extrudable elastomeric explosive comprising either RDX or PETN (pentaerythritol tetranitrate) distributed in a pourable silicone rubber. Silicone oil will not accept large amounts of RDX at room temperature. Generally, up to about a 1:1 weight ratio of RDX to silicone fluid can be practiced. In order to permit loading of larger amounts of RDX in silicone, the patent teaches heating the silicone rubber to about 66° C. (150° F.). This high mix temperature complicates and prolongs processing. An acid catalyst is then added to the silicone rubber for curing. Because the silicone is cross-linked, recovery of the RDX from the cross-linked composition is difficult.